In a food processor set up with the regular blade, place the flour and salt in and pulse 3 times to mix.
Add the butter and process until the flour is crumbly.
Add in the vinegar and the lemon zest.
Once the mixture is combined into course crumbs, start adding the water 1 tablespoon at a time. After the dough comes together, stop processing it.
Turn the dough out onto the counter and form it into 2 discs. Wrap them and refrigerate for at least 1 hour.
After the hour, use according to pie recipe directions
Add the filling and bake:
Roll out one disc of dough to create the bottom of the crust and line a 9 inch pie plate. Poke holes in the bottom with a fork and set aside.
In a large bowl, combine the blueberries, sugar, cornstarch, salt, zest, lemon juice. Toss to coat.
Pour filling into prepared pie plate.
Roll out the second piece of crust and then using a pizza cutter, cut strips of crust to form a lattice style top for the pie.
Place one strip through the middle of the pie and then arrange the other strips in a row from the middle.
Fold the strips in half and begin weaving strips of pie crust in the opposite direction.
Once the strips are arranged in a lattice or basket weave design, cut the longer pieces off and crimp the strips to the bottom crust to keep everything together.
With a basting brush, brush the egg wash onto the crust and top with sanding sugar or another coarse sugar like Turbinado.
Place pie into the 425 degree oven for 15 minutes. After which lower the temperature to 375°F and continue baking for 30 minutes.
After 30 minutes, check the pie and make sure the crust isn’t getting too dark. If it is, tenting with aluminum foil will prevent the crust from burning.
Once the pie is finished baking, this is the hard part—let it cool for at least 2-3 hours. If it’s cut into too soon it will be too runny. By letting it sit, the cornstarch has time to work its magic!
Serve with a scoop of vanilla ice cream and enjoy!
Notes
If you don't want a lattice top, roll out dough into a circle and lay on top of pie. Crimp edges together and cut slits in the top for venting. Brush with egg wash and add sugar as directed before baking.